In automation systems and conveyor systems, for example, there must be a safety system according to safety regulations. The safety system interrupts operation (e.g. running of automation system/conveyor system) when detecting that safety is somehow compromised.
Traditionally the safety systems have included one or more safety contacts fitted to measure position of doors, movement limits of the equipment etc. safety-related system parameters. During normal operation the safety contacts are closed. Opening of at least one safety contact indicates a potential risk.
The safety system outputs a safety signal after it has passed via a plurality of safety contacts. The passed safety signal goes further to one or more safety devices, such as circuit breakers. Opening of at least one of the safety contacts interrupts the safety signal, which causes the circuit breaker to switch off main circuit power, bringing the system to standstill.
More recently, electronic safety devices have been accepted as part of the safety systems. The electronic safety device means an electronic device performing safety-related operations, e.g. operations affecting the system safety. Such electronic safety devices may be, for example, drive components and brake control units of conveyor systems, in particular of elevator systems, escalator systems and moving walkways.
The electronic safety devices are specially designed devices to implement functional safety according to associated standards, such as safety standard EN IEC 61508.
As regards to the electronic safety devices in general, there is need for improvements.